This application is based upon and claims priority from Japanese Patent Application No. 07-237433 filed Sep. 14, 1995, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to image blur compensation devices, which are used in still cameras, video cameras, and other optical devices and instruments. In particular, it relates to image blur compensation devices reducing the effects of noise which becomes a problem during position detection using a Position Sensitive Device (PSD).
2. Description of the Related Art
Image blur compensation devices, which compensate for image blur arising due to camera vibration, caused by hand motions and the like during photography, normally compensate for image blur by moving at least one lens (hereinafter termed xe2x80x9cimage blur compensation optical systemxe2x80x9d) in a direction at right angles to the optical axis of the photographic lens. A general description of a prior art image blur compensation device is provided below.
FIG. 31 is a lateral cross sectional diagram showing an image blur compensation device. In FIG. 31, an image blur compensation optical system 1 is located in a lens barrel 2. Namely, the lens and the lens barrel are integral.
The lens barrel 2, as shown in FIG. 32, may be driven in the XY plane if the direction of the optical axis is the Z axis. Thus, the lens barrel 2 is driven at right angles to the Z axis in the direction of the XY plane by an electromagnetic actuator consisting of a coil 6, a magnet 7, a yoke 9, and a yoke 10.
The electromagnetic actuator constituted by the coil 6, the magnet 7, the yoke 9 and the yoke 10, consists of two sets of these elements located in mutually orthogonal directions. This structure generates respective forces in the X axis direction and the Y axis direction.
Namely, the image blur compensation optical system 1 is a structure which can move integrally with the lens barrel 2 in the X axis direction and the Y axis direction.
A slit plate 4 is located in the base edge side (yoke 9) in the sidewall of the lens barrel 2. An infrared light emitting element (IRED) 8 is located in the front end side of the lens barrel 2. The light beam of the IRED 8 is disposed to pass through a slotted hole (slit) in the slit plate 4.
Then, a position sensitive device (PSD) 5 is disposed in the yoke 9, which is fixed in position. The PSD 5, by detecting the light of the IRED 8 passing through the slit of the slit plate 4, detects the movement position of the image blur compensation optical system 1.
FIGS. 32(a)-(b) are cross sectional diagrams of the support structure of the image blur compensation optical system (lens barrel). FIG. 32(a) shows the state with the image blur compensation optical system in the optical axis position, and FIG. 32(b) shows the state with the image blur compensation optical system moved from the optical axis position.
As shown in FIGS. 32(a) and 32(b), the lens barrel 2 is cantilever supported by four elastic support members 3 (because FIGS. 32(a) and 32(b) are cross sections, only two are shown, 3a and 3b). The base end of support members 3a, 3b, are engaged with the yoke 9 and can move in a direction at right angles with respect to the optical axis.
FIG. 33 is a constitutional block diagram of a prior art image blur compensation device. In FIG. 33, the image blur compensation device is equipped with an angular velocity detection circuit (X axis) 13, an angular velocity detection circuit (Y axis) 14, a rangefinding circuit 18, a photometric circuit 19, a microcomputer unit (xe2x80x9cCPUxe2x80x9d) 20, a main switch 26, a half depression switch 27, a release switch 28, a power supply battery 29, an optical system 51, position detection elements 56X, 56Y, a lens position detection circuit (X axis) 57X, a lens position detection circuit (Y axis) 57Y, a lens position detection circuit (AF) 58, an actuator drive circuit (X axis) 59X, an actuator drive circuit (Y axis) 59Y, a shutter drive circuit (AF) 60, actuators 61X, 61Y, a stepping motor 62, a DC/DC converter 64.
In the above constitution, the image blur compensation operation is performed as summarized next. In FIG. 33, when half depression of the release button is performed, the half depression switch 27 is set ON, the DC/DC converter 64 starts, and the CPU 20 begins to provide a stabilized power supply.
When the rangefinding circuit 18 and the photometric circuit 19 begin the standard photographic operations of the camera, at the same time the angular velocity circuit (X axis) 13 and the angular velocity circuit (Y axis) 14 begin to detect the blurring motions of the camera. The angular velocity detection sensors use piezoelectric type angular velocity sensors which detect the normal Coriolis force.
The CPU 20 integrates the outputs obtained from the angular velocity sensors (blurring motion sensors) and converts them into blurring motion angles of the camera. Furthermore, it converts the output from the angular velocity sensors into target drive position data of the image blur compensation optical system 54.
Next, when full depression of the release button is performed, the release switch 28 is set ON, and the focusing lens 55 is driven with the stepping motor 62 being controlled by the shutter drive circuit 60. Simultaneously with this operation, control is also commenced of control of the image blur compensation mechanism by the image blur compensation optical system 54.
The control of the image blur compensation mechanism is accomplished by the actuator drive circuit (X axis) 59X and the actuator drive circuit (Y axis) 59Y in order to move the image blur compensation optical system according to the same target drive position data as at the time of half depression. The actuator drive circuits 59X and 59Y perform in phase by the difference of the target drive position data and the actual image blur compensation optical system position data, and send signals to the actuators 61X and 61Y.
Detection of the actual position of the image blur compensation optical system is wholly performed by the lens position detection circuit (X axis) 57X, the lens position detection circuit (Y axis) 57Y, and the CPU 20. The usual PSD is used in the position detection elements 56X, 56Y. The CPU 20 calculates the position of the image blur compensation optical system by the output current of the PSD.
The actuator drive circuit (X axis) 59X and the actuator drive circuit (Y axis) 59Y next supply drive currents to the actuators 61X, 61Y, based on the signals of the servo units.
The actuators 61X, 61Y, based on these drive currents, move the image blur compensation optical system in a plane at right angles to the optical axis, and effect compensation of the image blur, such as due to hand motions.
However, in the prior art, in the case of detection using a PSD of the position of the image blur compensation optical system, because the photoelectric current obtained from the PSD is a very small current, there were cases in which the position data could not be accurately detected, because of the effects of noise arising inside the camera and outside the camera.
As noise sources inside the camera, there are switching noise of the DC/DC converter which is in the power supply circuit, stepping motor drive noise when driving the shutter, motor noise when driving the focusing lens(es), and the like. However, it is difficult to bring about a reduction of these noises because they stem from the characteristics and character of their devices.
Accordingly, how to reduce these noises in a image blur compensation device using a PSD in position detection of the image blur compensation optical system has become an important problem.
Accordingly, it is an object of the present invention to solve the above problems of the prior art, and to provide an image blur compensation device which can effectively reduce the effect of noise.
Objects of the present invention are achieved by an image blur compensation device comprising an image blur compensation optical system to compensate for image blur arising due to blurring motion of an optical instrument, a position detection unit to detect the position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system based on the detection result of the position detection unit, and a power supply circuit to perform power supply to the position detection unit and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit the detection operation of the position detection unit, in a fixed period during which a switching phase of the power supply circuit has changed.
Further objects of the present invention are achieved by an image blur compensation device, comprising an image blur compensation optical system to compensate for image blur arising due to blurring motion of an optical instrument with a photographic lens, a position detection unit to detect a position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system based on the detection result of the position detection unit, and a focusing lens drive unit which drives the photographic lens to a focused position, wherein the image blur compensation drive unit includes an inhibition device to inhibit detection operation of the position detection unit, within an operation period of the focusing lens drive unit.
Still further objects of the present invention are achieved by an image blur compensation device comprising an image blur compensation optical system to compensate for image blur arising due to blurring motion of an optical instrument with a shutter, a position detection unit to detect the position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system, based on the detection result of the position detection unit, and a shutter drive unit to perform driving of the shutter, wherein the image blur compensation drive unit includes an inhibition device to inhibit the detection operation of the position detection unit within the operation period of the shutter drive unit.
Yet further objects of the present invention are achieved by an image blur compensation device comprising a blurring motion detection unit to detect the amount of blurring motion of an optical instrument, an image blur compensation optical system to compensate for image blur arising due to blurring motion of the optical instrument, a position detection unit to detect the position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system, based on an output result of the blurring motion detection unit and on an output result of the position detection unit, so as to suppress image blur, and a power supply circuit to perform power supply to the position detection unit, the blurring motion detection unit, and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit the detection operation of the position detection unit and the blurring motion detection unit, within a fixed period after a phase of the power supply circuit has switched.
Still further objects of the present invention are achieved by an image blur compensation device comprising a blurring motion detection unit to detect the amount of blurring motion of an optical device with an optical element, an image blur compensation optical system to compensate for image blur arising due to blurring motion of the optical device, a position detection unit to detect the position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system, based on an output result of the blurring motion detection unit and on an output result of the position detection unit, so as to suppress image blur, a focusing lens drive unit to drive the optical element to a focused position, and a power supply circuit to perform power supply to the position detection unit, the blurring motion detection unit, and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit a detection operation of the position detection unit and the blurring motion detection unit, within a period of operation of the focusing lens drive unit.
Even further objects of the present invention are achieved by an image blur compensation device comprising a blurring motion detection unit to detect an amount of blurring motion of an optical device with a shutter, an image blur compensation optical system to compensate for image blur arising due to blurring motion of the optical device, a position detection unit to detect the position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system, based on an output result of the blurring motion detection unit and on an output result of the position detection unit, so as to suppress image blur, a shutter drive unit to drive the shutter, and a power supply circuit to supply power to the position detection unit, the blurring motion detection unit, and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit the detection operation of the position detection unit and the blurring motion detection unit, within a period of operation of the shutter drive unit.
Other objects of the present invention are achieved by an image blur compensation device wherein the image blur compensation drive unit includes a cancellation device to cancel the inhibition of the detecting by the detection unit in cases in which a state of a driving operation by the shutter drive unit during shutter opening does not change in a predetermined time.
Still further objects of the present invention are achieved by an image blur compensation device, comprising a blurring motion detection unit to detect an amount of blurring motion of an optical device using film, an image blur compensation optical system to compensate for image blur arising due to blurring motion of the optical device, a position detection unit to detect a position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system based on an output result of the blurring motion detection unit and on an output result of the position detection unit, so as to suppress image blur, a shutter exposure control unit to control exposure of film in the optical device, and a power supply circuit to perform power supply to the position detection unit, the blurring motion detection unit, the shutter exposure control unit, and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit a switching control operation of the power supply circuit within a period of operation of the shutter exposure control unit.
Yet further objects of the present invention are achieved by an image blur compensation device comprising a blurring motion detection unit to detect an amount of blurring motion of an optical device with a shutter, an image blur compensation optical system to compensate for image blur arising due to blurring motion of the optical device, a position detection unit to detect a position of the image blur compensation optical system, an image blur compensation drive unit to drive the image blur compensation optical system based on an output result of the blurring motion detection unit and on an output result of the position detection unit, so as to suppress image blur, a shutter drive unit to drive the shutter, and a power supply circuit to perform power supply to the position detection unit, the blurring motion detection unit, the shutter drive unit, and the image blur compensation drive unit by a switching step-up control, wherein the image blur compensation drive unit includes an inhibition device to inhibit a switching control operation of the power supply circuit within a period of operation of a drive control of the image blur compensation optical system.
Moreover, further objects of the present invention are achieved by an image blur compensation device wherein the power supply circuit has at least one capacitor for backup use.